Vitrinite and inertinite were separated by DGC from Chinese Shenmu bituminous coal and the structural characteristics of the macerals, before and after pyrolysis, were analyzed by ultimate analysis, FTIR and C-13 NMR. The results showed that vitrinite chars always had higher H and lower C content than inertinite char at the same pyrolysis temperature. The FTIR and 13 C NMR indicated that vitrinite had more aliphatic C-H, hydrogen bonding and lower aromaticity. With increasing temperature, the aliphatic C-H decreased, aromatic C-H, aromaticity and H-ar/H-al ratio increased. At the same temperature, inertinite always had higher H-ar/H-al, ratio than vitrinite, which is consistent with that inertinite had higher aromaticity than vitrinite. And the H-ar/H-al ratio was also related to the remainder volatile matter. With increasing H-ar/H-al, ratio, the remainder volatile matter in vitrinite and inertinite decreased. The higher aromaticity and H-ar/H-al ratio and lower H content of the inertinite in all temperature range were correlated with its higher thermal stability and lower volatile yield than vitrinite. (C) 2002 Elsevier Science Ltd. All rights reserved.